The present invention relates to copper alloy conductors and their method of manufacture. More particularly, it relates to soft copper alloy conductors which are of a high electric conductivity and which have a softness and are useful soft copper alloy conductors for use as magnet wires, conductors for various types of machines and appliances, lead wires, etc. and to their method of manufacture.
Regarding magnet wires which are used in motors, transformers, etc., the requirements for good windability, little deformation after winding, etc. have become more severe as the compactness and high performance of such electrical machines and appliances have come to be demanded more and more. From this point of view, the softness of the conductors themselves is of very great importance, while improvement on the surface smoothness of enamel, i.e. the insulator of the wires, is also wanted at the same time.
For use as such magnet wires or the like wherein softness is a requisite property, a conductor material which, as compared with the tough-pitch copper and oxygen-free copper that have been heretofore in use, is more readily softened and produces a good softness easily, almost without any decrease in electric conductivity.
In recent years, on the other hand, the development of electronic machines and appliances has given rise to a tendency that conductors which have previously been coated with tin, lead or solder or the like have come to be used more and more as electric conductors and lead wires for the wirings inside and outside of such machines and appliances with a view to obtaining better solderability at the time of wiring and assembling work.
As material for such conductors, annealed tough-pitch copper wire has usually been greatly used heretofore. The coating treatment of such conductors is carried out by hot-dipping or electroplating.
The hot-dipping method is often found to be a preferable plating method for the plating of such metals with a low melting point as those already mentioned.
The reasons for this are that it is possible to make the plating at a high speed with comparatively simple equipment and that an annealed material is often considered desirable for the finished product and, in the case of conductors of a comparatively small diameter, conductors of a cold worked material becomes annealed by the heat applied to the conductors while they pass through the trough of the molten metal while their surface is coated with the coating metal at the same time, so that an annealing process in particular may be dispensed with in many cases.
In this connection, the present inventor has discovered from experience that in production on an industrial scale, problems occur such as the conductors are passed through the trough at a considerably high speed out of consideration of production efficiency and that if they are passed at a low speed, the conductors may get dissolved in the molten coating metal and detrimentally affect the properties of the coating metal or an intermetallic compound may be produced between the coating metal and the conductors which results in brittleness.
Furthermore, it has become more frequent in recent years to carry out solder coating. Since the melting point of solder is lower than those of tin and lead, the temperature of molten solder can be made lower than that of tin and lead, and a lower temperature is preferable for the purpose of preventing the properties of the molten metal from being deteriorated by the dissolving of the conductors in the melt trough and also for the purpose of energy saving. However, the condition at the present time is that the temperature of the molten metal is not lowered very much because of the consideration of the annealing of core conductors.
Circumstances being as mentioned above, hot-dip coated soft conductors which are manufactured by taking full advantage of the characteristic feature of the afore-mentioned plating by hot dipping without lowering the electric conductivity and without having the properties deteriorated by the formation of an intermetallic compound between the coating metal and the conductors and which can be manufactured more easily than conductors heretofore manufactured by plating tough-pitch copper conductors with tin, lead or solder are eagerly wanted. That is to say, hot-dip coated soft conductors which can be annealed during the dipping in the plating bath even if the heating duration is short and the temperature of the melt bath is lower as already mentioned are eagerly wanted.